Image forming apparatus

Abstract

An image forming apparatus includes an image processor configured to convert image data based on a first conversion condition; an image forming unit configured to form an image on a sheet based on the image data converted by the image processor, the image forming unit having an image bearing member on which the image is to be formed, a transfer unit configured to transfer the image from the image bearing member onto the sheet, and a fixing unit configured to fix the image to the sheet; a conveyance roller configured to convey the sheet having the image fixed thereto; a reading unit configured to read a pattern image on the sheet conveyed by the conveyance roller; and a detector configured to detect a pattern image on the image bearing member.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 an image processor configured to convert image data based on a first conversion condition; 
 an image forming unit configured to form an image on a sheet based on the image data converted by the image processor, the image forming unit having an image bearing member on which the image is to be formed, a transfer unit configured to transfer the image from the image bearing member onto the sheet, and a fixing unit configured to fix the image to the sheet; 
 a conveyance roller configured to convey the sheet having the image fixed thereto; 
 a reading unit configured to read a pattern image on the sheet conveyed by the conveyance roller; 
 a detector configured to detect a pattern image on the image bearing member; and 
 a controller configured to:
 control the image forming unit to form a first pattern image on a first sheet; 
 control the reading unit to read the first pattern image on the first sheet; 
 control the image forming unit to form a second pattern image on the image bearing member; 
 control the detector to detect the second pattern image on the image bearing member; 
 generate, based on a reading result of the first pattern image by the reading unit and a detection result of the second pattern image by the detector, a second conversion condition for converting the reading result of the first pattern image on the sheet to the detection result of the second pattern image on the image bearing member; 
 control the image forming unit to form a third pattern image on a second sheet; 
 control the reading unit to read the third pattern image on the second sheet; 
 convert a reading result of the third pattern image by the reading unit, based on the second conversion condition; and 
 update the first conversion condition based on the converted reading result of the third pattern image by the reading unit. 
 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the controller is configured to:
 control the image forming unit to form a fourth pattern image on the image bearing member; 
 control the detector to detect the fourth pattern image on the image bearing member; and 
 update the first conversion condition based on a detection result of the fourth pattern image by the detector. 
 
     
     
       3. The image forming apparatus according to  claim 1 , wherein the controller is configured to update the first conversion condition based on the converted reading result of the third pattern image by the reading unit and target data indicating a density of the pattern image on the image bearing member. 
     
     
       4. The image forming apparatus according to  claim 1 , wherein the controller is configured to control, when a time period that has elapsed since the second conversion condition was generated exceeds a predetermined time period, the image forming unit to form the first pattern image and the second pattern image in order to regenerate the second conversion condition. 
     
     
       5. The image forming apparatus according to  claim 1 , wherein the controller is configured to control, when the number of sheets subjected to image formation since the second conversion condition was generated exceeds a predetermined number, the image forming unit to form the first pattern image and the second pattern image in order to regenerate the second conversion condition. 
     
     
       6. The image forming apparatus according to  claim 1 ,
 wherein the controller is configured to acquire user instruction information indicating a transfer condition for causing the transfer unit to transfer the image onto the sheet, and 
 wherein the controller is configured to control, when the transfer condition of the transfer unit is changed based on the user instruction information, the image forming unit to form the first pattern image and the second pattern image in order to regenerate the second conversion condition. 
 
     
     
       7. The image forming apparatus according to  claim 1 ,
 wherein the image forming unit further includes a light source configured to expose a photosensitive member with light in order to form an electrostatic latent image, and a developing device configured to develop the electrostatic latent image through use of toner, 
 wherein the controller is configured to acquire user instruction information indicating a developing condition for causing the developing device to develop the electrostatic latent image, and 
 wherein the controller is configured to control, when the developing condition of the developing device is changed based on the user instruction information, the image forming unit to form the first pattern image and the second pattern image in order to regenerate the second conversion condition. 
 
     
     
       8. The image forming apparatus according to  claim 1 ,
 wherein the controller is configured to acquire user instruction information indicating a fixing condition for causing the fixing unit to fix the image, and 
 wherein the controller is configured to control, when the fixing condition of the fixing unit is changed based on the user instruction information, the image forming unit to form the first pattern image and the second pattern image in order to regenerate the second conversion condition. 
 
     
     
       9. The image forming apparatus according to  claim 1 , wherein the first pattern image is the second pattern image transferred onto the first sheet by the transfer unit and detected by the detector. 
     
     
       10. The image forming apparatus according to  claim 1 , wherein the first pattern image is a pattern image transferred onto the first sheet by the transfer unit without being detected by the detector. 
     
     
       11. The image forming apparatus according to  claim 1 , wherein the second sheet and the first sheet are sheets of the same type. 
     
     
       12. The image forming apparatus according to  claim 1 ,
 wherein the first pattern image includes a plurality of images having different tone levels, 
 wherein the third pattern image includes a plurality of images having different tone levels, and 
 wherein the number of tone levels of the plurality of images of the first pattern image is less than the number of tone levels of the plurality of images of the third pattern image. 
 
     
     
       13. The image forming apparatus according to  claim 1 , wherein the first conversion condition is a tone correction table to be used for correcting a tone characteristic of the image to be formed by the image forming unit. 
     
     
       14. The image forming apparatus according to  claim 1 , further comprising:
 a conveyor configured to convey the sheet, the conveyor having a reverse portion at which a front side and a back side of the sheet are reversed, and a common conveyance path through which both of the sheet having the front side and the back side reversed by the reverse portion and the sheet not having the front side and the back side reversed by the reverse portion are conveyed; and 
 a tray on which the sheet conveyed by the conveyor is to be stacked, 
 wherein the reading unit includes a first sensor configured to read a first surface of the sheet conveyed through the common conveyance path, and a second sensor configured to read a second surface opposite to the first surface of the sheet conveyed through the common conveyance path, 
 wherein the controller is configured to acquire user instruction information indicating a direction of a surface on which the image is formed of the sheet stacked on the tray, 
 wherein the controller is configured to control conveyance by the conveyor of the first sheet having the first pattern image formed thereon based on the user instruction information, and to control the first sensor to read the first pattern image, 
 wherein the controller is configured to generate a first conversion condition for the first sensor based on a reading result of the first pattern image by the first sensor and the detection result of the second pattern image by the detector, 
 wherein the controller is configured to control conveyance by the conveyor of the first sheet having the first pattern image formed thereon based on the user instruction information, and to control the second sensor to read the first pattern image, and 
 wherein the controller is configured to generate a first conversion condition for the second sensor based on a reading result of the first pattern image by the second sensor and the detection result of the second pattern image by the detector.